Humeanism starts out from the actual world and its basis of fundamental, non-modal facts. From this vantage point, a principle of `recombination' is used to span a range of possibility. According to this principle, any distribution of the perfectly natural properties in spacetime (and perhaps all different ways spacetime itself can be arranged) is possible. In other words, the local, intrinsic states of affairs are freely recombinable into novel possibilities, spanning the vast Lewisian pluriverse of all metaphysically possible worlds. At each of these worlds, the laws of nature are determined by the best system at that world.Another important caveat: [1]} himself takes Humean supervenience to be a contingent truth, as there might be “unHumean” worlds containing `alien' properties such that Humean supervenience fails. The best systems analysis may fail at those worlds. Thus, although the general template for a best systems analysis does not depend on spacetime, the Lewisian version certainly does in its construction of possible worlds and hence of the pluriverse, which forms the basis of Lewis's system.This is a necessary truth, as even the unHumean worlds are unified and isolated by spatiotemporal relations. In fact, for any reductive project such as Lewis's, a central task is to characterize the supervenience basis on which the laws are supposed to supervene. In light of the challenge articulated in §, the central question becomes whether or not this supervenience basis contains spacetime or spatiotemporal relations. For Lewis, it clearly does.
